Vulcanizing fuel



'Patented Jan. 9, 1940 UNITED srAras 8 Clalms.

is satisfactory, there is a tendency for the alumlnum to, cause too high a maximumtemperature,

the aluminum expensive* and the, resultant product decomposes to form hydrogen sulde, which is objectionable.

As is 'well' known, iron "has heretofore been known to be a combustible material under certain conditions. For example, iron filings will burn' in pure oxygen and iron will rust readily in the presence of water. It has heretoiore been suggested that under certain conditions a heating composition for vulcanizers might be obtained by igniting a`mixture of iron filings and sulfur, but under ordinary circumstances such ignition and burning is not easy -and therefore iron, except in combination with a vigorously burning metal such as aluminum or magnesium, has not been employed in vulcanizing patches.

This is particularly true with reference to tire vulvanizers, in which the amount of vulcanizing fue] is small and where the fuel isiexposed to the atmosphere or to large cooling areas.

It has now been discovered that iron filings may be produced which, when combined with sulfur, will ignite and burn satisfactorily and at the same time will eliminate the disadvantages present when aluminum is used. such a fuel is likewise less expensive than an aluminum base material.

Normal iron filings, as purchased on the market, are largely made urnof two classes of particles. The first type of particles is quite large and the structure thereof visible to the unaided eye. These particles are rough and jagged, but are too large to burn satisfactorily. The second class of particles are very small and their structure is not visible to the naked eye., Under a microscope these particles do not have the rough and jagged appearance of the larger partic es, but have a sintered or fused appearance, the individual particles under the microscope resembling small globules or shot-like masses. This type of iron filings will not burn in such manner as to make a satisfactory vulcanizing fuel, even though very fine in size.

It has been discovered, however, that if particles are chosen which do not have a sintered or fused surface and at the same time are in a very fine state of subdivision, a satisfactory vulcanizing fuel may be obtained therefrom.

The term follicular" is used herein to describe such partlcles, and designates that the particles have the rough jagged surface which is characteristic of large particles of ordinary filings such as the public is generally acquainted with.

The preferred iron material is produced by grinding, for example with an emery wheel, cast iron piston rings, for example, such rings having a carbon content of 33% and a silicon content of 434%. The product should be predominantly oi particles at least fine enough to pass a mesh screen and preferably above of the product will pass a mesh screen.

Temperature conditions during manuiacture o the product must be such as not to produce the fused' or slnteredparticles. With a brittle material such as cast iron piston rings an emery wheel may sometimes be employed in the production of 'particles, care being'taken not to heat them to a sintering or fusing point. However, with certain tough materials such as some oi the steels. an emery wheel is unsatisfactory unless great care is taken. In such cases -filing may be employed.

To the finely divided iron is added an accelerator, such as suliur, in the desired proportions.

A preferred fuel comprises 75% iron and 25% sulfur. The percentage of suliur may, however, be varied rather widely, but as it increases the product flames more in burning. A preferred range is from 15-40% sulfur, depending upon the use and the appliances with which used.

Other forms of iron may be used, for example, the product known as iron by' hydrogen is quite active. This product is very finely divided, can be ignited with a match and will burn in air alone without an accelerator, but it is preferred to add sulfur or other accelerator to speed up the burning. In this product about 25% suliur is preferred, with the range from 540% being satisfactory.

In some instances it may be desirable to employ in addition to the sulfur an accelerating agent. For example, a .90% carbo-n steel, ground to 150 mesh, burned satisfactorily when '75 parts were combined with 15 parts of sulfur and 10 parts of potassium permanganate, although less permanganate may be used. This steel will burn with red phosphorus alone, although a little permanganate or other rust promoter is preferred.

Other accelerators may be used instead of the sulfur. Red phosphorus, for example, is extremely satisfactory. For example, 20% of red phosphorus added to the iron by hydrogen will produce a satisfactory burning fuel.

Acidic substances, such as aluminum chloride, Zinc chloride and oxidizing substances such as potassium chlorate and sodium nitrate, may likewise be used as accelerators. certain types of iron require the use of accelerators other than sulfur in order to produce a satisfactory fuel. For example, in certain instances such as above shown, a combination of sulfur and permanganate may produce commercial results where the sulfur alone fails. These acid-forming substances and oxid'zing agents may be in general classed as rust promoters, in that all of them promote the oxidation of the iron. v

This type of fuel is particularly suitable for use with which is known in the trade as a heavy cup, that is, the fuel is burned in a heavy metallic cup which retains the heat of combustion for a suflicient time to vulcanize the rubber.

Steel of about 1.50 carbon content is also satisfactory, for example in combination with sulfur and permanganate in substantially the same proportons as for the 090% carbon steel. The 150% carbon steel when ground on an emery wheel produces elcngated fibres which are particularly desirable in that they will mat and not segregate.

The term "acceleratorfi' as used in the claims hereof, excludes aluminum.

A vulcanizing patch is illustrated dlagrammatically in the drawing, in which the' vulcanizing cup 5 is held in a clamp I by the screw 4 against a patch 6 which rests upon the tube 3.

` The tube is supported by the plate 2 of the clamp.

The vulcanizing fuel i3 is placed within the cup i, wherein it is 'retained by the flanges NI. A handle z may be provided on the cup.` In some instances the cup and Iuel maybe made integrally, the fuel being cemented to the cup.

In manufacturing fuel it isimportant that the particles be largely of thesame size and that no great variation occur therein. For instance, where most of the particles are approximately 200 mesh, substantially none of `the particles should be above 150 mesh and substantially none by weight should be below 300 mesh.,

What I claim as new and desire to secure by Letters Patent is:

1. A vulcanizing iuel consisting essentially of finely divided iron, substantially all of the particles of which will pass a 60 mesh screen, and a non-metallic accelerator. substantially all of the particles of the iron having a rough jagged surface.

2. A product as set forth in claim 1, in which the bulk of the iron particles will pass a 150 mesh screen.

3. A vulcanizing fuel as set forth in claim 1, in which the iron is cast iron.

4. A fuel as set toi-th in claim 1, in which the accelerator is sulfur.

5. A fuel as set forth in claim 1, in which the accelerator is a substance of the class consisting of sulfur and phosphorus. r

6. A vulcanizing fucl consisting of finelydivided iron substantially all of the particles of which will pass a 60 mesh screen, the particles of iron being rough and jagged and free from fused orsintered surfaces, and at least about 33 /a% of sulfur based upon the amount of iron.

7. A vulcanizing fue] as set forth in claim 1, in which the iron is cast iron of approximately &8% carbon content and 434% silicon content.

8. A vulcanizing fuel as set forth in claim 1, in which the accelerator is sulphur and the sulphur is present in an amount from 15% to 40%.

RALPH H. CHURCHILL. 

